Answer:
please find your answer in the attached picture, along with explanation.
Given
Car 1
m1 = 1300 kg
v1 = 20 m/s
m2 = 900 kg
v2 = -15 m/s
(Negative sign shows that direction of car 2 is opposite to car 1)
Procedure
As per the conservation of linear momentum, "The total momentum of the system before the collision must be equal to the total momentum after the collision". And this applies to the perfectly inelastic collision as well. Then the expression is,

Thus, we can conclude that the speed and direction of the cars after the impact is 5.68 m/s towards the first car.
Answer:
a) μ = 0.1957
, b) ΔK = 158.8 J
, c) K = 0.683 J
Explanation:
We must solve this problem in parts, one for the collision and the other with the conservation of energy
Let's find the speed of the wood block after the crash
Initial moment. Before the crash
p₀ = m v₁₀ + M v₂₀
Final moment. Right after the crash
pf = m
+ M v_{2f}
The system is made up of the block and the bullet, so the moment is preserved
p₀ = pf
m v₁₀ = m v_{1f} + M v_{2f}
v_{2f} = m (v₁₀ - v_{1f}) / M
v_{2f} = 4.5 10-3 (400 - 190) /0.65
v_{2f} = 1.45 m / s
Now we can use the energy work theorem for the wood block
Starting point
Em₀ = K = ½ m v2f2
Final point
Emf = 0
W = ΔEm
- fr x = 0 - ½ m v₂₂2f2
The friction force is
fr = μN
With Newton's second law
N- W = 0
N = Mg
We substitute
-μ Mg x = - ½ M v2f2
μ = ½ v2f2 / gx
Let's calculate
μ = ½ 1.41 2 / 9.8 0.72
μ = 0.1957
b) let's look for the initial and final kinetic energy
K₀ = 1/2 m v₁²
K₀ = ½ 4.50 10⁻³ 400²
K₀ = 2.40 10² J
Kf = ½ 4.50 10⁻³ 190²
Kf = 8.12 10¹ J
Energy reduction is
K₀ - Kf = 2.40 10²- 8.12 10¹
ΔK = 158.8 J
c) kinetic energy
K = ½ M v²
K = ½ 0.650 1.45²
K = 0.683 J
Answer:
Vf = 4.40 m/s and θ = 88º
Explanation:
To solve this problem, let's look for the resultants of the force and with this we calculate the accelerations in each axis.
Let's use trigonometry to break down the forces
Sin 25 = F1x / F1
Cos 25 = F1y / F1
Fix = F1 sin 25
F1x = 1.85 sin 25
F1x = 0.78 N
F1y = 1.85 cos 25
F1y = 1.67 N
F2 = - 0.782 N j ^ (south)
F3 = - 0.750 N i ^ (west)
We write Newton's second law
X axis (East-West)
F1x - F3 = m ax
ax = (F1x - F3) / m
ax = (0.78 - (0.750)) / 0.325
ax = 0.092 m / s²
Y axis (North-South)
F1y - F2 = m ay
ay = (1.67- (0.782)) / 0.325
ay = 2.73 m / s²
Let's calculate the magnitude and direction of the acceleration
a = RA ax2 + ay2
a = RA 0.092² + 2.73²
a = 2.73m / s²
tan θ = ay / ax
θ = tan⁻¹ (2.73/0.092)
θ = tan⁻¹ 29.67
θ = 88º
We calculate the speed, notice that we use the total acceleration to be able to use the totol displacement
Vf² = vo² + 2 at D
Vf² = 0 + 2 2.73 3.55
Vf = √ 19.38
Vf = 4.40 m / s
θ = 88º